A known impact detecting apparatus used in a vehicle is disclosed in U.S. Pat. No. 4,533,801. This impact detecting apparatus includes a housing possessing a conical slope, a ball located on the conical slope, a pair of fixed electrodes made of elastic material, and a movable conductor located between the fixed electrodes to provide connection to an electric power source. The movable conductor is capable of being bent by an external force so that the electric power is disconnected. In this apparatus, when an impact greater than a predetermined value is applied, the ball moves on the conical slope and bumps into the movable conductor to cause the movable conductor to bend. When the electric power is disconnected, the impact detecting apparatus outputs an impact signal.
However, in this apparatus, the conical slope in the housing is inclined at the same angle in all directions of the conical slope and so movement of the ball occurs regardless of the impacting direction. Therefore, the sensitivity of the apparatus does not vary in proportion to the impacting direction. It is thus difficult to adjust the sensitivity of the apparatus based on the vehicle frame structure upon collisions from different directions of the vehicle.
In light of the foregoing, a need exists for an impact detecting apparatus that is not susceptible to the same drawbacks and disadvantages discussed above.
It would be desirable to provide an impact detecting apparatus that allows the sensitivity of the apparatus to be selectively set or predetermined.